1. Field of the Invention
The present invention relates to a light-sensitive material, more particularly, the present invention is concerned with a light-sensitive nameplate material which comprises an aluminum (hereinafter, this term includes aluminum and its alloys) support having a porous aluminum oxide film on the surface thereof and a light-sensitive layer comprising an o-quinone diazide provided on the aluminum oxide film.
2. Description of the Prior Art
A method of producing a semi-permanent dye image in which a light-sensitive liquid is coated on a porous aluminum oxide film, which is brought into intimate contact with a transparent positive, printed, and developed, and then areas where the aluminum oxide film has been exposed are dyed with a dye and fine pores therein sealed is known as one method of producing aluminum oxide nameplates. These processings are described in detail in Kinzoku Hyomen Gijyutsu Binran (Handbook of Metal Surface Technology), edited by Kinzoku Hyomen Gijyutsu Kyokai (The Metal Finishing Society of Japan), published by Nikkan Kogyo Shinbun Sha, Tokyo, New Edition (Dec. 30, 1973), p. 842-852.
Hitherto, dichromic acid salt light-sensitive agents have been mainly used as light-sensitive materials for aluminum oxide nameplate materials, and, in particular, a dichromic acidfish glue light-sensitive material has been widely used. Light-sensitive agents of this kind, however, undergo reaction even in the dark, and should be used in a day or two after coating. So far as the inventor knows, therefore, light-sensitive aluminum oxide nameplate materials are not now available on the market.
Nameplate manufacturers, therefore, have conducted all processing such as the anodic oxidation of aluminum, coating the light-sensitive material, exposure, development, dyeing, peeling of resist, and sealing of pores in their own companies. Conventional aluminum oxide nameplate materials thus require extensive time and labor to be processed. Furthermore, these materials suffer from the disadvantages that processing requires high skill, the finished articles lack uniformity, and desired articles cannot easily be produced on special order. In addition, waste liquid from development contains hexavalent chromium, which is a toxic pollutant.
To solving these problems, it has been considered to use diazonium salts and light-sensitive resins which do not undergo reaction in the dark. However, light-sensitive plates produced by coating such light-sensitive materials on aluminum oxide films are inferior in stability with time, and the inventor's experiments have revealed that such a light-sensitive plate cannot be developed more than one day after coating. The reason for this is believed to be that upon coating the light-sensitive material part of the coating material goes into the fine pores of the aluminum oxide layer, and cannot be removed with ease at the time of development.
West German Pat. (OLS) No. 2,353,499 describes a method in which in order to prevent penetration of the light-sensitive coating material into the fine pores the fine pores are sealed by heating after anodic oxidation, the light-sensitive material being coated on the fine pores so sealed.
In accordance with this method, in exposed areas upon development, and in areas where etching is conducted using a mixed liquid of potassium dichromate and sulfuric acid, fine pores are again produced, are dyed and resealed, thereby producing nameplates. While this method improves the stability with time of light-sensitive materials, it suffers from the defect that the number of processing stages increases. In addition, this method requires dichromic acid salts for etching, which are undesired from the point of environmental pollution.